1. Field of the Invention
This invention relates to an internal combustion engine and more particularly to an improved internal combustion engine system which emits very little or no noxious gaseous material into the atmosphere and at the same time undergoes no loss of power and fuel economy and a method of operating same.
2. Description of the Prior Art
As is well known in the interest of environmental protection it is highly desirable to develop an internal combustion engine which produces little or no pollution produces usable amounts of power and at the same time does not use unduly large amounts of gasoline (i.e. is economical).
Many attempts have been made to develop an internal combustion engine of the type described above but as yet a completely successful working model has not been produced. Some engines thus far proposed have approached a successful solution but have suffered from at least one major drawback. For example, the so-called torch ignition type engine has under some modes of operation managed to reduce the emissions of NOx, CO and HC to desirable levels but at the expense of enormous complexity of the cylinder head and carburetor and/or injection system, i.e. the cylinder head is formed with not only a main combustion chamber but a pre or torch chamber, inlet passages to both, inlet valves for each and an air fuel mixture supply system which maintains a necessary difference between and varies according to the operational mode of the engine the air fuel ratios of the air-fuel mixture separately fed to each chamber. The production assembly and maintenance of such a complex cylinder head is of course undesirable. Other disadvantages of the torch ignition engine are, the large internal surface area of the two chambers, which invariably means a high HC emission concentration, and the rather poor fuel consumption characteristics exhibited at low speed, RPM modes of operation.
In contrast to the complex torch ignition engine, a dual spark plug rotary engine has been proposed. The simplicity of the single combustion chamber and only two spark plugs on paper seems ideal, nevertheless it has been plagued with rather serious problems of sealing the ends of the rotor or rotors, trochoidal housing wall chatter and poor fuel economy.
This wankel type rotary engine has met with some initial success due to its light weight and high power output characteristics but the long term use of this unique design is still in doubt at this time.
A number of reciprocating type counterparts of the twin spark plug rotary engine have also been proposed. Like the rotary engine these have usually used non synchronous sparkings of the plugs in an effort to stably ignite lean to very lean air fuel mixtures. Some of these have exhibited rather outstanding fuel economy but have lacked power especially during the acceleration mode of engine operation.
In some cases the above described reciprocating dual spark plug engines have employed a small amount of exhaust gas recirculation in an effort to further reduce the NOx generation already partially reduced by the employment of the lean air fuel mixture. However as the rate of EGR is raised the combustion in the combustion chambers becomes unstable and emission levels of HC and CO immediately rise, not to mention the power output falls almost to zero.
One arrangement which has met with some success is an engine operated on a rather lean air fuel ratio which is ignited by two synchronously sparked plugs, employs EGR to further suppress NOx generation and is followed by a lean type thermal reactor which receives exhaust gases through siamesed lined exhaust ports; the latter being provided in an attempt to maintain the critically necessary high temperature to promote secondary oxidation.
However it is still necessary to provide an internal combustion of the aforementioned type which is improved simpler in construction and does not suffer from any lack of performance, especially during acceleration due to operation on a lean air fuel mixture.